Sphebometeb for



STATES.

PATENT GEPHAS' JOHNSON, OF SOUTHINGTON, CONNEGTICUT.

SPHEROIVLETER FR; ASCERTAINNG THE RELATIVE. BEARING OF PLACES," 850,'

Specificationlof Letters Patent No:V 568, datedy January 9, 1838.

rometei.l or coursing instrument Vand I' hereby declare that the followingv isa Vfull andf exact description oli the same asin-v ventedl by me. c Y The instrument may be made of brass` or any other suitable material.

lt is composedprincipally of. three circu# lar plates, of which the bottom` plateA, is the largest, the central plate is the smallest, and the upperrplate projects` over the centralplate E which is hidden. by yit is the perspective view. `The threeV plates'are united by screws D, D,- in a horizontal position.` On. the base or bottom plate A the degrees of latitude are marked ninety' degrees on each quarter, making in the whole three hundred and siXtyl degrees,l beginning at either end of an equinoctial circle placed on` the upper plafte, and meeting inA the quadrant of the circle on either side of the equinoctial. circle, or at what maybe called the poles of the. instrument.

A circular ring B- called a sliding. meridian, lies inV a horizontal position between the lower and the upper plates,I andV around,

the central! plata/around which it revolves when requirech On the' outer side of this ring' and opposite to, eachY other are two' smaller semicirculfar plates F, F united at their' bases with. the edges of. the ring B in? a vertical position, and called( compass plates.. marked thepoints1 of the; compass in their order, half of the pointsbei'ng on each* plate the eastern pointsbeingmarlnedl on the. pla-tel on the western side ot the instrument, and the westernpoints on the pl-ate on theeasternside of the instrument. 'Oni each plate the east or west pointis on the upper sideof its respective plate. On the upper horizontal circular plate is a semicircula'r plate G placed VinL a vertical position and united! at its. base to the'horizontalcirculai" plate across its center.4 V The circular edge of this scn'iic'ircular plate has a bevelx ony each side,

On these semicirculan' plates .are

Y and is graduated on each bevel with the degrees of longitude, being one hundred and eighty degrees' onv each side on each bevel,

beginning at each angle subtendedr at eachy end. oii the base;- the degrees marked onthesouth. sid-cof the semicircle beginningon the 'west side of the instrument,and the degrees lon the north side of the semicircle begin'.-V ningV on the east side of the instrument; This is called theequinoctia'l circle. Con-rl nected' with the sliding or revolving meridian. is the semicircular segment. of a ring H lof one hundredl and] eighty degrees,l attached to the outered-ges where the semicircula-r plates are' united t@ the circular ring or lslid-ing lmeridian, and turning. on. pivotsv upon the innerl center of the basesof the compass plates.- The inner edge of this seg,-r

vment of a ring, is beveled' on each side; the

segment itself` being calledv a: prime: vertical-l Theends-o the prime'vertica-l are so'fo'rmed-v that by havinga shoulder, project over the` circular edge ofthe compass plat-es' totheA outer surface for the purpose-of comply'in-gqV inits movement with the desired latitude', it

corresponds with 'the points of compass y marked: on the compass plates.` The inner edge of the prime rvertical is graduated.onl each bevel one hundred and'eighty degrees; the graduation on'k the bevel ot thesouth side commencing where the endg of the primeverftical is connected7 with the compass pla-te onth'e western. side of the instrument, and' the graduationon thegbevel ofV the north side commencing where thev prime vertical' is connected with. the compassplate on. the'v easternside ot the instrument;v l I I,

Attachedor connected by pivots with' theV upper horizontal circular plate is another segment of a. ring- I, ot one hundred and eighty.l degrees turning on; those pivots,- the pivots being entered into' the upper circular plate at the ends of a: diagonal drawnacros's the center of the plate at a right4 angle" With the equinoctial circle and corresponding with the pol'esof. the instrument. .This seg-1 ment ofa ring is calledl a movable meridian, having' both its: inner anda its outer edges beveled .on both' sides' and graduatedwitlifk ninety degrees on they bevels of the outerl side-1 in the'` fol-lowing mannerff Commencing' f of the other side opposite either', to correspond with the eastern points of compass on the compass plates.

The instrrunent is exhibited with its various parts in the annexed drawing, which is made a part of this specification.

The object of the instrument is to deter mine the true point of compass in all latitudes and longitudes, and to lay courses and measure distances in all directions on any part of the globe. In using it to determine the point o-f compass of one place from another: Move the sliding meridian so that one compass plate shall have the center of its base correspond with the degree of latitude of the place 'from which the course is calculated; the direction to be taken whether east or west determines the compass plate the instrument.

that is to be used; that is, if an eastern course is to be found, use the compass plate marked with the eastern points on the western side of the instrument; and if a western course, use the compass plate marked with the western points on the eastern side of Then find the difference of longitude between the two places on the equinoctial circle, and bring the movable meridian to that degree, which denotes the difference of longitude. Then bring the -prime vertical to` the latitude of the last place being found on the movable meridian,

and the point of compass with which the prime vertical corresponds on the compass plate used, will be the course from the first to the last place, but this will not hold vice versa from the last to the first place; but the course must be determined in the same 'way as the above.

For example: to find the direction in which Genoa `lies from Quito: Quito being under the equator and eighty degrees of longitudewest of Greenwich, and Genoa forty live degrees of north latitude and ten degrees of east longitude, making forty five degrees of difference of latitude, and ninety degrees of difference of longitude between the two p'daces: bring the center of the compass plate marked with the eastern points of the compass to the equator for Quito. Then bring the movable meridian to ninety degrees marked on the south side of the equinoctial circle, because the places differ ninety degrees in longitude. Then bring the prime vertical to forty five degreesV on the northern part of the movable Ineridian for Genoa, The point with which the prime vertical corresponds on the compass plate will be found northeast, which is the direction` in which Genoa lies from Quito.

ABut it does not follow, Aas lis generally supposed, and laid down in books that Quito is southeast from Genoa.

To determine the course from Genoa to Quito: bring the center of the compass plate marked with the western points of Compass Vlish miles.

to forty five degrees marked on the north side of the base plate for Genoa. Bring the movable meridian to ninety degrees on the'north side of the equinoctial circle for the difference of longitude of the two places. Then bring the prime vertical to the center of the movable meridian for the latitude of Quito. The prime vertical will be found to correspond on the `compass with the west point, which is the direction of Quito from 7,5 G eno-a; that is, Genoa is northeast of Quito, and Quito is west of Genoa. The instrument being in the position above mentioned, counting the number of degrees on the prime vertical to where it corresponds with` the movable meridian, shows the-'distance from one place to the other in geographical miles. le thus find that Genoa is distant from Quito liBOOgeographical miles or 6265 Eng- Also running by log: knowing the ships course, and rate of sailing, the latitude and longitude of the ship are readily determined by using the instrument; and days run or reckoning is quickly calculated without reference to tables.

For the more perfect understanding of the principles of my invention, I subjoin the following remarks.

Every oneV knows the necessity of ascertaining practically the precise point of compass especially in navigation: and yet the methods in common use are incorrect. They furnish a near approximation to the true course in the vicinity of the equator, but not in higher latitudes. In sailing from one port to another in high latitudes, or if either place be in a high latitude, the course by compass must be constantly varied in order to sail in the most direct manner, of which the winds and current will admit. Any two places on the equinoctial line are east. and west from each other. But in approaching the polesv two places in the same latitude are not east and west from each other, but increase in variation from the 11e equator to the poles. A place sailed for on the equator being 90 degrees distant in longitude from the place of departure, the place sailed for is east or west from the place of departure, let that place be in what latitude it may. In other words, a place on the equator 90 degrees distant in longitude, is east or west from a place in any latitude on i that meridian. The prime vertical being a circle passing through the zenith of a place and'crossing the equator 90 degrees distant from the'place, uniting at the nadir of the place; the pointswhere the prime vertical crosses the equator being the east and west points; a ship sailing toward one ofA these points iinds as it approaches vthe equator that the point toward which it sails, recedes along the equator, being constantly 90 degrees distant from the place the ship is in.

If a ship in a high northern latitude 13e should sail for a port in the same latitude with the place of departure, and should sail east by compass, making that course good, it would fallv south of the port of destination. So, if the port of destination be in a higher or a lower latitude than the place of departure, calculating the course on the incorrect principle that two places in the-same latitude are east and west from each other', the ship would fall south of the port of destination. f

A ship having the course by compass correctly calculated land making that course good, would make north of the port of destination if in a northern latitude, and south if in a southern latitude, because the point recedes on the equator as the ship approaches it.

The equinoctial line is every point of compass from either pole; that is, the equinoctial line is both north and south from the North Pole and north and south from the South Pole. The North Pole is north and south of the South Pole. The South Pole is north and south of the North Pole. The South Pole is east of the North Pole. The North Pole is east of the South Pole. The Antipodes are both east and west from each other.

If the equinoctial line be south of the North Pole, sailing directly south by compass, would make the equator by the shortest course. Sailing north from the equator by compa-ss, a ship would make the North Pole by the shortest course, and would then constantly revolve aboutit; and sailing any other point of compass would constantly sail around the globe in a spiral direction, approaching the equator but not arriving at it; and the nearness of the spiral line would increase or diminish, according as the point approached the pole or the equtor. The same reversed may be said of the southern hemisphere. The spheriodal form of the earth increases this variation: that is, if the earth were an exact globe, the east and west points would cross the equator at 90 degrees distant. The ealrth being spheroidal or flattened at the poles, the eastern and western points cross the equator at less than 90 degrees distant.

The dip of the needlevalso in approaching' the poles inclines thev points still nearer to each other than the ololateness itself. But the variation, which the instrument herein before described is intended to obviate arises from the globular form of the earth. If the earth were of a cylindrical form, and parallels of latitude drawn upon it, two places in the same latitude would be east and west from each other. If the earth were a plane, the same would hold true. If the earth were in the form of two cones united at `their bases, and parallels of latitude drawn upon them, calling their union the equator and their vertices the poles, the

points would vary according to the 'elevation of the cones.

But at 'the greatest p'ossible elevation two places in the sainev lati` tnde would not be east and'v west of 'each other.

rThe preceding assertions can be clearly demonstrated by reference to Van artificial terrestrial globe, and still more impressively by using the cylindrical, plane, or conical' tor-ms just mentioned. p For demonstration on a globe: mark 'circular bit of paper in the form of compass card, and lay it on diierent parts oftV Again, place the card on Quito, and pass it 5' one degree of longitude toward Genoa. lIheY northeast point passes south of it. This shows, that if we would sail a direct course to a place, we must constantly vary the point of compass. Use the same card on a cylinder marked with parallels of latitude. Genoa would be northeast of Quito, and Quito southwest of Genoa; and continuing one point of compass from one to the other, would make the place. Try the same eX- periment on a plane, and the'result will be the same. Place the card on different parts of the cones united at their bases as I have stated, and the appearances will be the same as I have mentioned in regard to cones.

The instrument may be made of any convenient size.

I do not claim any one of the parts of the instrument, which I have described, taken simply as my invention or improvement: but

I do claim as my invention or improvement- The combination above specified of the several parts of the said instrument, namely, the compass divided into two separate parts set vertically on the opposite sides of a circle, having the eastern points on'one part, and the western points on the other partthe part on which the western points are marked standing on the eastern side, and that, on which the eastern points are marked, standing on the western side of the instrument: the prime vertical in the form of a semicircle. 'attached to the compass plates, turning at its ends to correspond with said plates, beveled on the inneredge, graduated for measuring geographical miles,

and having shoulders, projecting to indicate the point of compass: the movable merdian in the form of a semicircle, beveled on both edges, intersecting at once the prime vertical and equinoctial circle. and turning on pivots at the ends: the sliding meridian moving horizontally around a circular plate: the equinoctial circle set vertically, beveled on its circular edge7 and graduated on both bevels, commencing at opposite ends on each bevel the junction of the equinoctial circle at its base with a circular plate-all combined and made to move in the manner `hereinbefore set forth to produce, and, by

such combina-tion and movements of the movable parts, producing the effect of ascertaining the relative bearings of places, directing a ship by the shortest course from one place to antother, running lines, and determining true distances.

Dated at Middletown the 14th day of Feb` ruary A. D. 1837.

CEPHAS JOHNSON. In presence of- XVM. H. CHILD7 ONA BARNES. 

